Doorwall bay rotting against stamped concrete patio

osprey41August 8, 2013

Hope some gurus can weigh in here.

I have a 6 year old house (pic attached) that's mostly brick, but is wood in a few areas like the doorwall bay (as shown). 4 years ago, had a stamped concrete patio installed right up to the bay. I believe a vapor barrier was put in place, but as you can imagine, the wood underneath the doorwall (both the trim directly underneath and supporting wood behind the trim) are now starting to rot. The patio covers up about 6" of the bay and is separated by (from what I can tell) only a fabric concrete expansion strip.

I've had several carpenters come out to quote on fixing it, but the estimates and fixes have varied from trying to take out the concrete steps and replacing wood with fake "PVC wood" to just chiseling out the rot, replacing the trim and flashing everything to prevent further water intrusion.

Any thoughts on the best path forward for repair? I may end up contracting out the work, but am not particularly savvy with regard to wood rot and making an appropriate fix. Perhaps it's something I can fix myself.

One other concern is that there is a small-ish air gap under the bay to gravel / earth / crushed concrete beneath - if I fixed the trim and prevented water intrusion from outside, will I still get burned by moisture under the bay? (The patio installed assured me no, but he was selling a patio).

so the bay cantilvers out from the main foundation and is the fascia boards at the ends of the joists that form the backside of the concrete slab/stairs. I assume there is still a cavity space behind the stairs and below the bay (unless they filled it all in with concrete, too).

Can you cut throught he floor in the bay and repair and properly flash the patio from the backside?

I think if you start chipping the concrete stairs it might be difficult to pour a nice patch without really hurting the aesthetics. (i.e. matching the color of the concrete, cracks at teh cold junction, etc.)

There is a space beneath the bay, but it's partially filled in with crushed concrete. Going at the problem from inside isn't really an option (or at least I'd like it to not be an option) because inside the bay is tile floor that extends into the kitchen and dining room. One suggestion I was given was to cut out 4 inches above the steps all the way across, possibly try to chip out some of the rotted wood, but mostly just leave it there, put in a piece of cedar or PVC trimboard with flashing behind it, and then caulk it all in, prime, and paint. Is that a good idea? My hope is that once I stop the water infiltration from the step (if that's where the problem is - I assume it is), then I can just leave the rotted wood underneath to dry out and it won't be a problem. Thanks for your reply.

Thank you for the responses. I was giving this some more thought and am thinking of removing the rotten trim and then flashing and retrimming (keeping a good eye on the caulk bead over the years). My thought is that if I can keep water from seeping down the wall and getting behind the patio (between the patio and the wood) then I should be able to stop the water infiltration and thus, further rot damage. Does this make sense? Basically I'm not going to allow water to get between the patio and the bay. Any downsides to that? Would that possibly stop the problem?

We had a similar situation where a concrete pad for a set of steps was poured against the front wall of the house, to above the concrete foundation level and above the sill plate that sat on it. There was originally flashing to keep water away from the join but over the years it corroded away and the water rotted out the sill plate. That and a couple of other pieces of bad design rotted out the entire corner of the house, which we had to have rebuilt.

While you might keep an eye on the flashing and caulking, how about future occupants of your house? Will the knowledge that this must be done get passed on, or lost? Caulk is not a long term solution.

One possibility for a long term solution might be to remove the concrete steps entirely, while keeping the patio, and build wood steps from the patio up to the doors.

I am also worried about your cantilevered joists. Did they put a vapor barrier down (like what you'd see in a crawlspace) to keep ground vapor from coming up and causing damage to your cantilevered joists?